# [Retros] Retros Digest, Vol 146, Issue 2

roberto osorio osorio.arg at gmail.com
Fri Sep 2 09:33:27 EDT 2016

```Wow, another non-believer in the power of knights! :o)
***********************************************************************
knights were powerfull some 10 centuries ago :o)

Nice, just orthogonal moves but a diagonal mate.

(49,0,0) in 7.0 moves:  1. h4 h5 2. T-h3  Th6  3. Ta3 Tf6  4. Txa7 Txf2
5.Ta3 Ta4  6.Tg3 Tf4  7. Tg7 Txf1#
This is 3.5 displacement per ply. The maximum for 100% orthogonal moves?

The first Francois´example is less than 2 (5.5 moves). The minimum?

2016-09-02 9:55 GMT-03:00 Francois Labelle <flab at wismuth.com>:

> Dominique Forlot wrote:
>
> 1.Cg1-f3 Cb8-c6 2.Cf3-e5 Cc6-d4 3.Ce5xd7 Cd4xe2 4.Cd7xf8 Ce2-f4 5.Dd1-h5
> Fc8-g4 6.Ff1-c4 Fg4-d1 7.Dh5xf7
>
>  mat(0,17,7)
>  D(13ply) = 39,69410640
>  vitesse 3.053393/ply  (and not 2.5117/ply !! :o(  ).
>
>
> But the PG you gave is a mate(0,16,8), so it's even better:
> distance = 40.515961
> speed = 3.116612/ply .
>
>
> Dominique Forlot wrote:
>
> "Compose the shortest sound checkmate PG witch beat the slowest speed
> record"
>
> the mat(4,4,0)  9.656854 lenght for 9 plies for example have a speed of
> :1,0729837...and the lower limit of the speed  is ... 1
>
>
> There is no mate(4,4,0) in 9 plies, my mate(4,4,0) was in 6 plies.
>
> Among all sound checkmate PGs in 6.0 moves or less, the slowest average
> speed is 1.112967 obtained from (8,3,0) in 11 plies:
>
> 1. e3 f6 2. e4 Kf7 3. e5 Kg6 4. e6 Kg5 5. d3+ Kh4 6. g3#
> 1. f3 b6 2. f4 Bb7 3. f5 Qc8 4. f6 Kd8 5. fxg7 f6 6. gxf8=Q#
> 1. f3 b6 2. f4 Bb7 3. f5 Qc8 4. f6 Kd8 5. fxg7 f6 6. gxf8=R#
> 1. h3 b6 2. h4 Bb7 3. h5 Qc8 4. h6 Kd8 5. hxg7 h6 6. gxf8=Q#
> 1. h3 b6 2. h4 Bb7 3. h5 Qc8 4. h6 Kd8 5. hxg7 h6 6. gxf8=R#
>
> The fastest average speed is 4.740194, coming from (38,10,0) in 11 plies
>
>
> Dominique Forlot wrote:
>
> To specify my thought on the problem of the matt by "knight alone" :
>
> because of mat(∅,∅,c) : « Knights alones» is unsound [...]
>
> *Compose a sound checkmate PG wicth "maximize" the geometric score =
> c*sqr(5) - (α + β*sqr(2))*
>
>
> In 6.0 moves or less, the best score I get is 26.832816 for (0,0,12):
>
> 1. Nf3 Nf6 2. Ne5 Ne4 3. Nxd7 Nxd2 4. Nxb8 Nxf1 5. Nd2 Ne3 6. Nf1 Nxg2#
> ... 4. Nxf8 ...
> ... 4. Nb6 ...
> ... 4. Nc5 ...
> ... 4. Ne5 ...
>
> What was your proof that mate(0,0,c) is unsound? :o)
>
>
> roberto osorio wrote:
>
> Three geometrical types of moves: orthogonal, (2,1), diagonal, i.e., N,
> SQR5, SQR2.
> Due to the opening, the task of 100% moves of just one type for a
> checkmate is only feasible for (N,0,0).
>
> I found a sound one in 14 single moves. Is there some one shorter? Surely
> this is easy to asnwer for Francois.
>
>
> Wow, another non-believer in the power of knights! :o)
>
> For (N,0,0), the shortest is in 5.5 moves, with N going from 21 to 29 in
> 5.5 moves, and from 25 to 41 in 6.0 moves:
>
> (21,0,0) in 5.5 moves: 1. d4 a5 2. d5 Ra6 3. d6 Rxd6 4. Qxd6 f6 5. Qxf6 h6
> 6. Qg6#
> (29,0,0) in 5.5 moves: 1. d4 h5 2. d5 Rh6 3. d6 Rxd6 4. Qxd6 a6 5. Qxa6 f5
> 6. Qg6#
> (25,0,0) in 6.0 moves: 1. a4 a5 2. Ra3 Ra6 3. Rc3 Rd6 4. Rxc7 Rxd2 5. Rxd7
> Qxd7 6. b3 Rxd1#
> (41,0,0) in 6.0 moves: 1. h4 h5 2. Rh3 Rh6 3. Rd3 Ra6 4. Rxd7 Rxa2 5. Rd3
> Qxd3 6. f4 Qg3#
>
>     François
>
>
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